Image projection apparatus

ABSTRACT

An image projection apparatus that can be attached to a vehicle and can be effectively utilized for acquisition of road surface condition information, detection of a hidden vehicle, and the like is provided. The image projection apparatus that projects an image includes: an acquisition unit that acquires information related to a vehicle; an image projection unit that projects an image based on the information acquired by the acquisition unit; and imaging means that acquires an image outside the vehicle, the image projection unit projects light in a wavelength band centered on a wavelength of 1.4 μm and the imaging means provides the information related to the vehicle by imaging an image projected based on the light in the wavelength band centered on the wavelength of 1.4 μm.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/163,703, filed Feb. 1, 2021, which is a continuation of U.S. patentapplication Ser. No. 16/801,229, filed on Feb. 26, 2020, now U.S. Pat.No. 10,933,800, which is a U.S. patent application Ser. No. 16/529,519,filed on Aug. 1, 2019, now U.S. Pat. No. 10,611,296, which is acontinuation of U.S. patent application Ser. No. 16/148,824 filed onOct. 1, 2018, now U.S. Pat. No. 10,434,933, which is a continuation ofU.S. patent application Ser. No. 15/565,231 filed on Oct. 9, 2017, nowU.S. Pat. No. 10,118,537 and claims priority under 35 U.S.C. § 119 ofJapanese Patent Application No. 2015-080720, filed on Apr. 10, 2015, andinternational Patent Application No. PCT/JP2016/060612, filed on Mar.31, 2016, the entire contents of which are hereby incorporated byreference.

TECHNICAL FIELD

The present invention relates to an image projection apparatus.

BACKGROUND ART

An image projection apparatus typified by a projector has already beenused in various fields as an apparatus for projecting a desired image inan enlarged manner, and it has been widely used as a display device fora personal computer and a cellular phone in recent years.

Regarding such an image projection apparatus, those listed below havealready been known as prior art techniques particularly related to theuse in a vehicle.

RELATED ART DOCUMENTS Patent Documents

-   Patent Document 1: Japanese Patent Application Laid-Open Publication    No. H08-43781-   Patent Document 2: Japanese Patent Application Laid-Open-   Publication No. 2004-136838-   Patent Document 3: Japanese Patent Application Laid-Open Publication    No. 2010-26759-   Patent Document 4: Japanese Patent Application Laid-Open Publication    No. 2012-247369-   Patent Document 5: Japanese Patent Application Laid-Open Publication    No. 2014-153868-   Patent Document 6: Japanese Patent Application Laid-Open Publication    No. 2013-213792

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

Namely, Patent Document 1 described above discloses a projection typedisplay apparatus which uses a vehicle headlight as an external lightsource by disposing an LCD projector, which incorporates no light sourceand is excellent in portability, in front of the vehicle headlight. InPatent Document 2, a first state in which the projector is incorporatedin front of the headlight in the vehicle in advance and a second statein which the projector or the headlight is moved to emit light flux fromthe headlight directly to the outside of the vehicle are realized forsolving a problem of Patent Document 1, and further an embodiment inwhich an image is displayed on a road is disclosed.

Also, an apparatus for vehicle driving support which, in order toeffectively arouse attention of a driver of a vehicle at the time ofdetermination of lane departure, displays information for promotingattention on a road ahead of a vehicle by irradiation means (laser)attached to a headlight part in front of the vehicle is known by PatentDocument 3.

In addition, an apparatus which is provided with a projector asprojection means attached at a front part of a vehicle and projects aroute guide image for guiding the vehicle in a branching direction basedon route information searched by a navigation system on a road surfaceahead of the vehicle, with a setting of a projection angle is alreadyknown by Patent Document 4. Further, an apparatus for vehicle drivingsupport which enables recognition of a place where a vehicle is headingby projecting a drawing pattern made up of target marks and trackinglines on a road surface ahead of the vehicle based on a traveling stateof the vehicle, and thus enables proper driving based thereon is alreadyknown by Patent Document 5.

Meanwhile, a technique which provides a camera in a vehicle asphotographing means for acquiring an image of a road surface ahead ofthe vehicle and estimates a condition of the road surface based on theimage from the camera is already known by Patent Document 6.

However, in the conventional techniques related to the projectordescribed above, the projector is used only for displaying informationsuch as the traveling state of a vehicle obtained from outside on a roadsurface, and functions of the projector are not necessarily utilizedeffectively. Also, in a case where the road surface condition ahead ofthe vehicle is detected by using Patent Document 6 described above, anecessary road surface image cannot be acquired under sunlight in thedaytime in particular due to strong sunlight, and it is difficult toaccurately estimate the road surface condition.

Thus, the present invention has been made in view of the problems in theconventional techniques described above, and an object thereof is toprovide an image projection apparatus capable of effectively utilizingfunctions of an image projection unit which is a projector attached to avehicle (mobile body typified by an automobile or the like).

Means for Solving the Problems

To solve the problems mentioned above, for example, a configurationdescribed in CLAIMS is adopted. The present application includes aplurality of means to solve the problems and an example thereof is animage projection apparatus that projects an image, and the imageprojection apparatus includes: an acquisition unit that acquiresinformation related to a vehicle; an image projection unit that projectsan image based on the information acquired by the acquisition unit; andimaging means that acquires an image outside the vehicle, and further,the image projection unit projects light in a wavelength band centeredon a wavelength of 1.4 μm and the imaging means provides the informationrelated to the vehicle by imaging an image projected based on the lightin the wavelength band centered on the wavelength of 1.4 μm.

Effects of the Invention

According to the present invention, it is possible to provide an imageprojection apparatus that can effectively utilize the functions of theimage projection unit attached to the vehicle including the acquisitionof road surface condition information, the detection of a hiddenvehicle, and the like.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 is a front perspective view of a vehicle which mounts an imageprojection apparatus according to an embodiment of the present inventionand projects an image on a road surface or the like;

FIG. 2 is a rear perspective view of a vehicle which mounts the imageprojection apparatus according to the embodiment of the presentinvention and projects an image on a road surface or the like;

FIG. 3 is a diagram illustrating an overall configuration of a lightcontrol ECU constituting the image projection apparatus;

FIG. 4 is a block diagram illustrating a further detailed configurationexample of the light control ECU and its peripheral elements;

FIG. 5 is a diagram illustrating an example of a configuration of theimage projection apparatus according to the embodiment of the presentinvention;

FIG. 6 is a ray diagram including an image plane of a projector;

FIG. 7 is a diagram for describing spectral intensity of sunlight and1.4 μm wavelength light of AM1.5 used in the present invention;

FIG. 8 is a diagram for describing acquisition of road surface conditioninformation using the projected 1.4 μm wavelength light, in the vehiclewhich mounts the image projection apparatus according to the presentinvention;

FIG. 9 is a diagram for describing an example of use of the acquiredroad surface condition information;

FIG. 10 is a diagram for describing another example of synthesizing the1.4 μm wavelength light with image light from an image projectionapparatus in the image projection apparatus; and

FIG. 11 is a diagram for describing detection of a vehicle hidden behinda blind spot using the projected 1.4 μm wavelength light, in the vehiclewhich mounts the image projection apparatus according to the presentinvention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described indetail with reference to the accompanying drawings.

<Arrangement of Image Projection Apparatus>

First, FIGS. 1(A) and 1(B) illustrate a passenger car as an example of avehicle 10 which mounts an image projection apparatus according to anembodiment of the present invention, and as illustrated in thesefigures, a pair of left and right headlights 11 is provided in front ofa main body of the vehicle (passenger car) 10. In the example of FIG.1(A), although not illustrated in detail here, a lamp as a light emitteris incorporated in each of the pair of headlights 11. Also, in theexample of FIG. 1(A), a pair of left and right image projectionapparatuses described in detail below is mounted in the vehicle(passenger car) 10. Then, image light from the image projectionapparatuses is projected ahead of the vehicle (passenger car) through,for example, transparent window parts. In this example, an imageprojected on a road surface or the like indicates a current orsubsequent traveling direction to a pedestrian or the like walking nearthe vehicle (passenger car), thereby ensuring higher safety.

FIG. 1(B) illustrates an example in which only one image projectionapparatus is mounted on a front part of a vehicle body. In this case,image light from the image projection apparatus is projected ahead ofthe vehicle (passenger car) 10 through, for example, a transparentwindow part 12 provided on the front part of the vehicle body.

Subsequently, FIGS. 2(A) and 2(B) illustrate a rear side of thepassenger car 10 which mounts the image projection apparatus accordingto the embodiment of the present invention, and as illustrated in thesefigures, red tail lamps 13 and 13′ are provided on the rear side of thevehicle body. Further, in the example of FIG. 2(A), although notillustrated in detail here again, a lamp as a light emitter isincorporated in each of these tail lamps 13 and 13′. Also, in theexample of FIG. 2(A), a pair of left and right image projectionapparatuses is mounted, and image light from the image projectionapparatuses is projected behind the vehicle (passenger car) 10 through,for example, transparent window parts.

FIG. 2(B) illustrates an example in which the image projection apparatusis mounted near the roof of the vehicle body. In the example of FIG.2(B), similarly to the example of FIG. 1(B), the image light isprojected behind the vehicle (passenger car) 10 through a transparentwindow part provided on a rear end of the vehicle body.

In the foregoing, examples in which one or plural (for example, a pairof) image projection apparatuses are mounted on the front, back, left,and right of the vehicle 10 have been described, but the presentinvention is not limited to these, and the image projection apparatusmay be mounted at any location (for example, a side mirror part, on theroof, side and bottom of the vehicle body) of the vehicle 10. Also, theimage projection apparatus may be integrally incorporated in theheadlight or the tail lamp. Namely, in the present invention, the imageprojection apparatus may be mounted at any location as long as a desiredimage can be projected on the road surface or the like by the imageprojection apparatus. In a case where the image projection apparatus isintegrally incorporated in the headlight or the tail lamp, a lightsource of the headlight or the tail lamp can be used also as a lightsource for projection.

<Configuration of Light Control ECU>

Subsequently, FIG. 3 illustrates an example of a configuration of anelectronic control unit (light control ECU) mounted in the passenger car10 described above. As apparent from the figure, a light control ECU 40includes a central processing unit (CPU) 41, RAM 42 and ROM 43 asstorage means, and an input/output device (I/O unit) 44. The lightcontrol ECU receives information input from a various informationacquisition unit and a communication unit described below via the I/Ounit 44, and controls driving of the headlight 11 and image projectionof an image projection apparatus 500.

Note that the information from the various information acquisition unitincludes, for example, a speed signal indicating a traveling speed ofthe vehicle, a signal indicating an engine state (ON/OFF), gearinformation indicating a gear position, a hazard signal notifyingsurrounding drivers of existence of danger, a steering wheel anglesignal indicating a steering angle of a steering wheel, a turn-signalsignal indicating presence/absence of a turn signal (referred to also asa “blinker”) and which of the left and right is lighting/blinking, andfurther lamp lighting information indicating lighting/blinking states ofthe various lamps.

The information from the various information acquisition unit furtherincludes, for example, information from an external light sensor whichdetects light outside the vehicle (illuminance signal, chromaticitysignal, and the like), image information from a camera attached to thevehicle, a signal from a distance sensor which detects a distance toanother vehicle running around the vehicle 10 such as in front of it orother objects, and further a signal from an infrared sensor whichdetects a situation outside the vehicle in the nighttime.

In addition, the information from the communication unit includes, forexample, a GPS (Global Positioning System) signal for determining aposition of the vehicle 10, so-called navigation information that isinformation from a navigation device which performs route guidance andthe like, and further information of inter-vehicle communicationperformed with another vehicle and road-to-vehicle communicationperformed between the road and the vehicle.

FIG. 4 illustrates a further detailed configuration of the light controlECU 40 and its peripheral elements described above. Namely, signals froma direction indicator sensor 51, a steering wheel angle sensor 52, ashift position sensor 53, a vehicle speed sensor 54, an acceleratoroperation sensor 55, a brake operation sensor 56, an illuminance sensor57, a chromaticity sensor 58, an engine start sensor 59, and a hazardlamp sensor 60 are input to the light control ECU 40. Further, a signalfrom a camera 61 is input to the ECU 40 via an image processing unit 62,and signals from a GPS receiving unit 63 and a map information outputunit 64 are input to the ECU 40 via a calculation unit 65. As will bedescribed in detail later, for example, a signal in a certain wavelengthband out of the signal from the camera 61 can be calculated as roadsurface condition information including unevenness of the road surfaceon which the vehicle 10 is running by subjecting it to a predeterminedprocessing in the calculation unit 65 or the ECU 40 described above.

Also, a projector 100 constituting the image projection apparatus 500receives a control signal input from the light control ECU 40 and asignal input from a projection signal output unit 110 (image signalprojected on the road surface or the like) via a control unit 120,whereby projection of an image onto the road surface or the likedescribed below is executed.

In addition, the light control ECU 40 further receives signals inputfrom a headlight sensor 66 and a high/low sensor 67.

<Image Projection Apparatus>

Subsequently, an example of a further detailed configuration of theimage projection apparatus 500 including the projector 100, theprojection signal output unit 110, and the control unit 120 illustratedin FIG. 4 will be described below with reference to FIG. 5 .

A projection optical system 501 is an optical system for projecting animage onto the road surface or the like, and includes a lens and/or amirror. A display device 502 is a device which generates an image bymodulating transmitting light or reflecting light, and for example, atransmissive liquid crystal panel, a reflective liquid crystal panel, ora DMD (Digital Micromirror Device) panel (registered trademark) is used.A display device driving unit 503 sends a driving signal to the displaydevice 502, and causes the display device 502 to generate an image. Alight source 505 generates light for image projection, and a highpressure mercury lamp, a xenon lamp, an LED light source, a laser lightsource, or the like is used. A power source 506 supplies power to thelight source 505. Further, the power source 506 supplies necessary powerto each of other units. An illumination optical system 504 collects anduniformizes the light generated by the light source 505, and emits thelight to the display device 502. A cooling unit 515 cools each part tobe in a high temperature state such as the light source 505, the powersource 506, or the display device 502 by an air cooling method or aliquid cooling method as necessary. An operation input unit 507 is anoperation button or a light receiving unit of a remote controller, andreceives an operation signal input from a user.

An image signal input unit 531 is connected to an external image outputdevice to receive image data input from the external image outputdevice. An audio signal input unit 533 is connected to an external audiooutput device to receive audio data input from the external audio outputdevice. An audio output unit 540 is capable of outputting audio based onthe audio data input to the audio signal input unit 533. Also, the audiooutput unit 540 may output an incorporated operation sound or errorwarning sound. A communication unit 532 is connected to, for example, anexternal information processing device to input and output variouscontrol signals.

A nonvolatile memory 508 stores various data to be used in a projectorfunction. The data stored in the nonvolatile memory 508 includes picturedata and image data prepared in advance for the projection onto theroad. A memory 509 stores the image data to be projected and controlparameters of each unit of the apparatus. A control unit 510 controlsoperation of each of connected units.

An image adjustment unit 560 performs image processing to the image datainput by the image signal input unit 531 and the picture data and theimage data stored in the nonvolatile memory 508. The image processingincludes, for example, scaling processing that performs enlargement,reduction, and deformation of the image, brightness adjustmentprocessing that changes brightness, contrast adjustment processing thatchanges a contrast curve of the image, and retinex processing thatdecomposes the image into light components and changes weighting foreach component.

A storage unit 570 records the image, picture, audio, and various data.For example, the image, picture, audio, and various data may be recordedin advance at the time of product shipment, or the image, picture,audio, and various data acquired from an external device, an externalserver, or the like via the communication unit 532 may be recorded. Theimage, picture, various data and the like recorded in the storage unit570 may be output as a projection image via the display device 502 andthe projection optical system 501. The audio recorded in the storageunit 570 may be output as audio from the audio output unit 540.

As described above, the image projection apparatus 500 can mount variousfunctions. However, the image projection apparatus 500 does notnecessarily have to include all the configurations described above. Theimage projection apparatus 500 may have any configuration as long as ithas a function of projecting the image.

FIG. 6 is a ray diagram of a projector including an image plane. In thisfigure, the image light, which is emitted from the light sourceconstituted of an LED or the like (not illustrated) and transmitsthrough the image display device, passes through a filter and the like,is refracted by various lens systems, and is further reflected inaccordance with the configuration, and is then projected on an imageplane 8 (road surface or the like).

In this manner, in the image projection apparatus 500 described above,the length of the long side of the range of the projection image is10061-542≈9519 9520 mm with respect to the projection distance of 700mm, and thus an unprecedented wide angle of view with the projectionratio of 700/9520=0.07 is realized.

In the foregoing, one image projection apparatus 500 and the projectionoptical system thereof have been described, but as described above, oneor plural (for example, a pair of) projectors may be mounted on thevehicle (or integrally incorporated in the headlights or tail lamps) inthe present invention so that a desired image is projected on the roadsurface or the like. At that time, in a case of the plural (for example,the pair of) image projection apparatuses 500 as illustrated in FIG.1(A) and FIG. 2(A) in particular, the same image may be projected on theroad surface or the like from each of the image projection apparatuses500 (in this case, the same image is displayed on the display device 502of FIG. 5 ), or different images may be projected from the left andright image projection apparatuses 500 and synthesized together on theroad surface or the like (in this case, an image obtained by dividingthe desired image into left and right is displayed on the display device502 of FIG. 5 ).

In the foregoing, as the image projection apparatus 500 that projectsthe image on the road surface or the like, the configuration using thetransmissive liquid crystal image display device has been described, butthe present invention is not limited thereto. For example, a reflectiveimage projection apparatus 500 constituted of a micromirror such as aDLP (Digital Light Processing) apparatus and an image projectionapparatus 500 capable of projecting image light from a light modulableplanar light emitting diode via the projection optical system can alsobe used as the image projection apparatus 500 in addition to thatdescribed above. Namely, in the present invention, any image projectionapparatus 500 may be used as long as the desired image can be projectedon the road surface or the like by the image projection apparatus 500.

Note that, in the present invention, the image projection apparatus 500described in detail above is used not only for displaying informationsuch as a traveling state of the vehicle 10 obtained from varioussensors and devices on the road surface like in the conventionaltechnique, but also for making it possible to accurately obtain roadsurface condition information that is a condition including unevennessof the road surface in the traveling direction of the vehicle 10, andfurther to detect another vehicle existing near the vehicle 10 buthidden behind a blind spot.

<Acquisition of Road Surface Condition Information>

In the following, a configuration for accurately obtaining road surfacecondition information and its function of the image projection apparatus500 will be described, but prior to that, its principle will bedescribed first.

FIG. 7 is a graph of spectral intensity of sunlight, and illustratesspectral intensity outside the atmosphere by a broken line and spectralintensity (solar altitude 42°) in the atmosphere by a solid line. Asapparent from the graph, since some of the wavelength components ofsunlight outside the atmosphere indicated by the broken line areabsorbed by the ozone layer and the H2O component in the atmosphere,some of the spectral components thereof are reduced or eliminated in thespectral intensity on the ground referred to as “AM1.5” indicated by thesolid line. In particular, the intensity is substantially zero (0) inthe wavelength band centered on a wavelength of 1.4 μm in the nearinfrared region. Namely, on the ground where the vehicle 10 runs, thesunlight does not contain a component of the wavelength of 1.4 μm.

Thus, various studies by the inventors of the present application havefound that, if the light in the wavelength band centered on thewavelength of 1.4 μm (hereinafter, simply referred to also as “1.4 μmwavelength light”) is used, it is possible to avoid the influence by thesunlight. Therefore, in the present invention, based on the findings bythe inventors of the present application described above, a techniquecapable of stably obtaining road surface condition information withoutbeing affected by the sunlight by using near infrared light in thewavelength band centered on the wavelength of 1.4 μm is proposed.

Specifically, as illustrated also in FIG. 8(A), a traveling state of thevehicle and other various types of information are displayed on the roadsurface and image light 200 containing 1.4 μm wavelength light 201described above is projected on the road surface by the image projectionapparatus 500 attached in front of the vehicle 10. In that case, forexample, it is preferable to project a light image (hereinafter,referred to also as “sensing projection image”) 202 in which the 1.4 μmwavelength light is formed into a lattice (mesh) shape made up ofmultiple rectangles.

Meanwhile, the camera 61 attached to the vehicle 10 receives lightincluding reflected light of the 1.4 μm wavelength light 201 on the roadsurface, and generates an image signal including a traveling roadsurface. At this time, if image processing based on the 1.4 μmwavelength light is performed in the calculation unit 65 or the ECU 40,it is possible to accurately obtain the road surface conditioninformation that is the condition including unevenness of the roadsurface in the traveling direction of the vehicle 10, without beingaffected by the sunlight.

At this time, if the image light 200 containing the “sensing projectionimage” 202 described above is projected, it becomes possible to easilyestimate the unevenness on the road surface by capturing the light imagein a lattice (mesh) shape deformed depending on the shape on the roadsurface including the unevenness by the camera 61 as illustrated in FIG.8(B). Note that the light image in the lattice shape to be projected ismade to be an image whose lattice spacing becomes wider as the image isfarther from the vehicle 10, whereby decrease in resolution of animaging device due to oblique imaging can be prevented.

Regarding the road surface condition information acquired as describedabove, an image for giving warning of the presence of unevenness on theroad surface may be displayed by the image projection apparatus 500, orthe warning may be transmitted to a driver by audio through a speaker inthe vehicle. Alternatively, the road surface condition information canbe used for controlling the brake and active suspension of the vehicle10 via the ECU 40 illustrated in FIG. 4 . Further, the road surfacecondition information can be transmitted to another vehicle by aninter-vehicle communication function of the communication unitillustrated in FIG. 3 .

In particular, in a case where the image projection apparatus 500projects the image indicating various types of information on the roadsurface, an image compensated with the condition of the road surfacethat is a projection plane of the image can be displayed by using theroad surface condition information as illustrated in FIG. 9 , so thatsatisfactory display without depending on the condition of the roadsurface is possible.

Here, in the case of projecting the 1.4 μm wavelength light describedabove, if the light source (see reference 505 of FIG. 5 ) has aconfiguration capable of emitting light containing a near infrared rayof 1.4 μm (including an infrared laser, for example) in the imageprojection apparatus 500 illustrated in FIG. 5 , it is sufficient if afilter that can transmit the 1.4 μm wavelength light when light from thelight source is modulated into projection light by a liquid crystalpanel or the like (see the display device 502) is inserted on the liquidcrystal panel. Also, in the case of projecting the “sensing projectionimage”, it is sufficient if an image in a lattice (mesh) shape issynthesized with the 1.4 μm wavelength light and displayed on the liquidcrystal panel. In the case where the image in the lattice shape isdisplayed on the liquid crystal panel with the 1.4 μm wavelength lightand is then projected, it is preferable that the image is displayedintermittently in a short period of time that cannot be sensed by humanvision, for example, in consideration of a possibility of an adverseeffect on another image (driving information of the vehicle and thelike) projected simultaneously or sequentially.

Alternatively, it is apparent to those skilled in the art that it isalso possible to separately generate the 1.4 μm wavelength light 201 orthe sensing projection image 202 described above by a light source 210such as a semiconductor infrared laser in place of the above, andsynthesize the light with the image light 200 projected from the imageprojection apparatus 500 by synthesizing means 220 such as aphotosynthetic prism as illustrated in FIG. 10 . Also in that case, inthe case of generating the 1.4 μm wavelength light in particular, it ispreferable that the image is displayed intermittently in a short periodof time that cannot be sensed by human vision, for example, inconsideration of an adverse effect on another image (driving informationof the vehicle and the like) to be projected.

<Detection of Vehicle Hidden Behind Blind Spot>

Subsequently, an example in which the image projection apparatus 500 isconfigured to detect another vehicle existing near the vehicle 10 buthidden behind a blind spot will be described below.

FIG. 11 illustrates an example in which the vehicle 10 and anothervehicle 10′ stop at an intersection, and a reflector 300 made ofdisk-shaped metal is installed and embedded in the road surface at thecenter of the intersection in this example. Here, the other vehicle 10′is hidden by a building around the intersection, that is, the vehicle10′ stops at a position that is a blind spot of the vehicle 10.

Here, if the image light containing the 1.4 μm wavelength light 200described above is projected ahead of the vehicle 10 by the imageprojection apparatus 500, the 1.4 μm wavelength light 200 spreads in afan shape, and strikes the reflector 300 at the center of theintersection. Thus, the 1.4 μm wavelength light 200 is reflected on thereflector 300, and propagates around the reflector 300. Thereafter, the1.4 μm wavelength light 200 reaches the other vehicle 10′ stopping atthe blind spot and is reflected thereon, and propagates again along theroute described above to return to the vehicle 10.

Then, if the reflected light of the 1.4 μm wavelength light 200 isdetected by detection means such as the camera 61 described above (seeFIG. 4 ), it is possible to detect the other vehicle 10′ hidden behindthe blind spot. Note that an example in which the reflector 300 of the1.4 μm wavelength light 200 is installed at the center of theintersection has been described above, but the reflector 300 may have ashape other than the disk-shape, and may be installed at the corner ofthe intersection regarding the location thereof. Also, projection of the1.4 μm wavelength light is preferably displayed intermittently in ashort period of time as described above.

In the foregoing, an example in which the image projection apparatus 500that generates the 1.4 μm wavelength light is installed in front of thevehicle 10 corresponding to the traveling direction thereof has beendescribed in detail, but the present invention is not limited thereto,and the image projection apparatus 500 may be provided on the rear sideof the vehicle 10.

Note that various embodiments of the present invention have beendescribed above, but the present invention is not limited to theembodiments described above, and includes various modification examples.For example, the above embodiments have described the entire system indetail in order to make the present invention easily understood, and thepresent invention is not necessarily limited to those having all thedescribed configurations. Also, a part of the configuration of oneembodiment may be replaced with the configuration of another embodiment,and the configuration of one embodiment may be added to theconfiguration of another embodiment. Furthermore, another configurationmay be added to a part of the configuration of each embodiment, and apart of the configuration of each embodiment may be eliminated orreplaced with another configuration.

In addition, regarding the configurations, functions, processing units,processing means, and the like described above, some or all of them maybe realized by hardware designed with integrated circuits. Also, theconfigurations, functions, and the like described above may be realizedby software by interpreting and executing a program for realizing eachfunction by a processor. Information such as a program, a table, a file,and the like for realizing each function can be stored in a recordingdevice such as a memory, a hard disk, or an SSD (Solid State Drive) or arecording medium such as an IC card, an SD card, or a DVD.

REFERENCE SIGNS LIST

-   -   10 vehicle (passenger car)    -   11 headlight    -   12 window part    -   13, 13′ tail lamp    -   40 light control ECU    -   61 camera    -   62 image processing unit    -   500 image projection apparatus    -   501 projection optical system    -   502 display device    -   503 display device driving unit    -   504 illumination optical system    -   505 light source    -   531 image signal input unit    -   533 audio signal input unit    -   532 communication unit

The invention claimed is:
 1. An image projection system for projectingan image on a road surface from a vehicle, comprising: the imageprojection system comprises a plurality of projectors including aninformation image projector and a sensing light projector; a cameraconfigured to image the road surface outside of the vehicle; and acontroller configured to control the image projection system and thecamera, wherein the information image projector is configured tocomprise: a light source configured to irradiate a first light; a lightmodulator configured to modulate the first light from the light sourcebased on the information related to a vehicle input by the controllerand generate an information image; and a projection optical systemconfigured to project the information image generated by the lightmodulator on the road surface, wherein the sensing light projector isconfigured to project a second light for sensing on the road surface,and wherein the second light for sensing is a grid-shaped image on theroad surface, and the intervals between the grids in the grid-shapedimage of the second light for sensing on the road surface become wideras a distance from the vehicle increases.
 2. The image projection systemaccording to claim 1, wherein the sensing light projector is configuredto project a predetermined wavelength light for sensing on the roadsurface, and wherein the predetermined wavelength light for sensing islight of a wavelength of 1.4 μm.
 3. The image projection systemaccording to claim 1, wherein the light modulator is selected from agroup consisting of a transmissive liquid crystal panel, a reflectiveliquid crystal panel, and a digital micromirror device.
 4. The imageprojection system according to claim 1, wherein the light source isselected from a group consisting of a high pressure mercury lamp, axenon lamp, a LED light source, and a laser light source.
 5. The imageprojection system according to claim 1, wherein the controller isfurther configured to control the information image to compensate forthe road surface condition.